Multimorbidity: Addressing the next global pandemic
Journal: PLoS Medicine (2023)

Advances in translational scientific research and modern medicine have enabled substantial progress to be made in clinical practices around the world.And, while there are no doubts that inequities persist, these advances have contributed to significant improvements in life expectancy globally.It may come as no surprise, considering the advances made, that the number of people being diagnosed as multimorbid-with two or more chronic conditions, either physical, mental or both-has also progressively increased.In low-and middle-income countries (LMICs) the problem is ever more palpable.Plagued by inequitable access to research facilities, healthcare services, diagnostics, therapeutics and effective policy implementation, progress lags far behind that of high-income countries (HICs).Not only is there a disproportionately high prevalence of chronic multisystem infectious diseases, such as HIV and TB, the prevalence of non-communicable conditions, such as hypertension and diabetes, have also increased over the preceding decades [1].Historically, in many HICs multimorbidity has been attributed to advancing age [2].While this has been and will continue to be one of the primary drivers of multimorbidity, other socioeconomic and structural factors-such as income, education, and location-contribute significantly to an individual's likelihood of being diagnosed with multiple conditions.As a result, in socioeconomically deprived regions, multimorbidity is becoming increasingly evident in younger populations [3].The emergence of COVID-19 and the consequence now known as "long-COVID" which affects multiple organ systems simultaneously, as well as numerous other conditions, such as HIV infection, multisystem autoimmune conditions, cancer, diabetes, and mental ill-health have further highlighted the age indiscriminate nature of multimorbidity.How individual conditions should be managed in tandem with others, and by whom, is often at the heart of the debate when putting the theoretical management of multimorbid patients into practice.It is frequently the case that, at least in the initial stages of multimorbidity manifestation, the contribution of each individual condition is minimal or limited while the cumulative effect of the conditions combined pose a major problem, not only to the patient but also to individual caregivers.Medical anthropologists have proposed the theory of "syndemics" in which diseases are hypothesized to cluster and to interact with one another (the biological-biological interface) as well as with social and structural factors (the biologicalsocial interface) [4].This clustering of conditions is often considered predictable, for example obesity, diabetes, and hypertension.However, syndemic clusters have usually been observed in inductive studies, and empirical research has revealed unexpected clustering of chronic conditions, such as the extremely high prevalence of cardiovascular disease seen in younger adults living with HIV.Who leads patient care is often determined by which of the co-existing conditions is most complex to manage, thus defaulting to that specialist caregiver.The reality is that diverse